1. Field of the Invention
The invention relates in general to interfaces for fiberoptic communication networks, in particular, the invention relates to interfaces able to adapt, adjust or convert optical signals transmitted between different network units. The invention also relates to methods of using devices in such interfaces
2. Technical Background
FIG. 1 shows an example of a part of a fiberoptic communication network according to the prior art. The figure shows a subscriber or client unit 12 connected to a larger fiberoptic network 14 via an interface 10 and a multiplexer/demultiplexer 11. In a typical case the client may be a company which may also have its own fiberoptic network. The client may, for example, obtain access to the larger fiberoptic network 14 by an agreement with another company, which may here be called the provider. The provider may have several clients which all are connected to the larger fiberoptic network 14. The connection between the client unit 12 and the interface 10 is normally bi-directional, which in this document means that signals can be sent in two opposite directions, indicated by arrows in FIG. 1. The communication is in this case implemented via two optical fibers 16, 18. According to the shown example, also the communication between the interface 10 and the multiplexer/demultiplexer 11 takes place over two optical fibers 20, 22. The interface 10 is used to adapt the signals from the client unit 12 to the multiplexer/demultiplexer 11 and vice versa. The interface 10 may, for example, carry out wavelength conversion, amplification, noise reduction etc. The interface 10 normally includes means for converting optical signals from the client unit 12 to electrical signals and means for converting electrical signals to optical signals before they are transmitted to the multiplexer/demultiplexer 11. The interface 10 also normally includes means for converting optical signals from the multiplexer/demultiplexer 11 to electrical signals and means for converting electrical signals to optical signals before they are transmitted to the client unit 12. The conversion in the different directions may be carried out via transceivers 24, 26 which form part of the interface 10. The transceivers 24, 26 can be formed as pluggable modules which can be plugged into a circuit board.
The client unit 12 may be located at a shorter or longer distance from the interface 10.
It should also be mentioned that an interface 10 may not only be positioned between a client unit 12 and a multiplexer/demultiplexer 11. An interface 10 can also be used as a so-called repeater node in a fiberoptic communication path. An example of an interface 10 used as a repeater node is shown in FIG. 2. This figure shows that there may be several interfaces 9, 10, 13 connected after each the along a fiberoptic communication path.
An interface as described above can be quite expensive. In particular the transceivers that form part of the interface are often expensive.